> My advice is use LED instead of LCD.
> If you want to use LCD you must know that
> it requires a backplane strobe pulse to
> keep the display refreshed, otherwise
> it'll go blank.

        Yeah, but almost nobody actually bothers
        to drive an LCD _directly_.

        For a four-digit seven-segment LCD with
        one backplane I would use an MM5452 or
        MM5453, which drive 32 and 33 LCD segments
        respectively.

        These chips require only a resistor and
        capacitor (to produce the backplane strobe),
        and have a two-line interface to the micro-
        controller (clock and data).

        The comms protocol is trivial.

        For a four-digit seven-segment LCD with
        two backplanes I would use a PCF8577, which
        can drive up to 64 LCD segments.

        Again, only an RC pair is required, and the
        two-line interface is now IIC!  This allows
        the chip to share the comms bus with other
        devices (including other '8577s).

        The comms protocol is no longer trivial,
        but IIC software is readily available.

        As I recall, the original mailer needed to
        drive three LCD's...

        With '5453s this would require three chips,
        and they can't be connected to the same
        two clock and data lines.  They could share
        a data line, but would all need seperate
        clock lines.  This gives a total of four
        I/O lines required.

        With '8577s (and assuming static drive LCDs,
        that is, one backplane) three chips would
        again be needed.  But in this case all three
        chips could be connected to the same two-wire
        IIC bus and separately addressed.  So only
        two I/O lines required.

        Go to

                www.semiconductors.philips.com/search/

        to search for the PCF8577 data sheet (.pdf).

___Bob